718 



EXPERIMENT STATION RECORD. 



to youug- plantlet.'^ of wheat when grown in distilled water. The toxic 

 equivalent is the mininnnn weight of the .substance dissolved in 100 

 parts of distilled water which will kill the plant. The figures given in 

 the accompan}'ing table are the average of a large number of experi- 

 ments, and show the relative poisonous properties of the substances 

 named. The more common of the substances experimented with are 

 iiiven in the following table: 



Amount of different substances required to till vheot ]>lanilets in irater cultures. 



Effect of chemical media on the growth of fungi, L. Planchon 



{Ajut. ScJ. jy"t. Bot., S. .srr., 11 {1000), pj). l-24S.j>Is. 4,Jt(js. 63; ahs. 

 in Jour. Roy. Micros. Sac. \London\ 1900, Xo. .4,7^. .^^).— The results 

 of a large number of experiments on the growth of 20 species of 

 Dematiete in a number of ditferent nutrient fluids and chemical solu- 

 tions are given. The terms fumagoid, alternarioid, macrosporoid, 

 etc., are noted to denote the different growth forms in the various 

 species. The best culture medium was found to be potato acidified 

 b}' lying for a quarter of an hour in 1 per cent sulphuric acid. It is 

 found that plants of this class are more subject to morphological 

 diversity, depending on the chemical composition of the medium, than 

 are the Mucedinew. These modifications affect the vegetative change 

 more than the reproductive organs and are believed to be a mode of 

 defense against desiccation and the injurious effects of the medium. 

 The most common forms of such modifications are the thickening and 

 encysting of the cell wall, a change in the form of the filament itself, 

 the production of chlamydospores of isolated cells capable of germina- 

 ting, or of toruloid forms in which the mycelial filament has entirely 

 disappeared. All kinds of transitional forms between the extremes 

 were noted. The author, as a result of his investigations, regards 

 Dematiuni prdlvhmii and C/adosporii//// /ic/lH/n/m as distinct species. 

 Two new species of Altenaria are described, ^1. variant and A. 

 polpnorpha. 



